A wide variety of lock arrangements have been used for securing bars to a frame in a fixed position to support and retain lading carried by the frame during transport. These bars, commonly known as dunnage bars, are releasably secured at each end in the fixed position by locking devices that typically permit each bar to be completely disengaged from the frame and removed to unload the cargo.
In one such commercially successful dunnage bar locking arrangement heretofore marketed by applicant, the lock includes a saddle having a base and parallel sidewalls spaced from each other by a distance to receive and laterally capture an end of the dunnage bar. A latch is mounted on an end wall of the saddle at a position spaced from the saddle base, and is rotatable on the end wall about an axis parallel to the saddle base between a lower position at which the latch captures the dunnage bar against the saddle base between the sidewalls, and an upper position that permits removal of the dunnage bar end. A coil spring urges the latch against the saddle end wall, and cooperates with a detent integral with an end wall for preventing rotation of the latch from the lower position to the upper position unless the latch is moved against the spring force. A cam surface on the detent automatically moves the latch against the spring force as the latch is manually pivoted from the upper to the lower bar-locking position.
Another such dunnage bar lock arrangement of applicant is that described in U.S. Pat. No. 5,037,256, in which a bar of rectangular cross section has a lateral opening in one side of the bar adjacent to the end of the bar, and a saddle has a base and parallel sidewalls spaced from each other to receive the bar end on the saddle base between the sidewalls. Positioned beneath the saddle base is an L-shaped latch that has a leg which extends upwardly from the saddle base adjacent to the sidewalls, and a finger overlying and spaced from the saddle base by a distance corresponding to the cross sectional dimension of the bar end. The latch is pivotally mounted to the saddle beneath the saddle base, and a coil spring is captured between the saddle and latch bases for urging the latch finger to the position overlying the saddle base. The bar end engages a camming surface on the latch finger for pivoting the latch with respect to the saddle against the force of the spring so that the bar end is received within the saddle, with a locating pin on the saddle base received within the opening at the bar end. In this position, the bar end is locked beneath the latch finger and between the saddle sidewalls.
Applicant's U.S. Pat. No. 5,378,093 discloses a bar lock arrangement that includes a bar of rectangular cross section, a bar lock on each end of the bar for releasably latching the bar to a frame in a position for securing freight, and a swing arm attached to each end of the bar and pivotally mounted to the frame for swinging the bar from the latched position to a remote position for loading or unloading freight while keeping the bar captive to the frame. The bar lock has a spring-biased latch bolt projecting outwardly from the bar for receipt by a striker plate positioned on the frame opposite each end of the bar when the bar is in the latched position. The striker plate has an aperture for receiving the latch bolt to latch the bar. A cable is attached to the latch bolts at both ends of the bar simultaneously to retract the bolts from the apertures to unlatch both ends of the bar. The swing arm is secured on a pivot cantilevered from a mounting bracket affixed to the frame side bars to permit the locking bar to be pivoted about the common axis of the spaced pivots.
Although applicant's prior lock arrangements described above have enjoyed substantial commercial acceptance and success, further improvements remain desirable. For example, in the locking arrangement disclosed in the parent application, the bars are mounted to the frame for horizontally locking the dunnage in position on the frame, while a separate lock arrangement is provided for vertically clamping the dunnage within the frame. Furthermore, in the lowered or unlocked position of the bar in applicant's parent application, the bar is loose, which is to say the bar is not rigidly secured to the frame. If an empty frame is shipped with the locking bar loose in this unlocked position, the lock arrangement can be damaged. It is therefore a general object of the present invention to provide a frame assembly for shipment of dunnage that improves upon applicant's prior lock arrangements in these and other respects. Another object of the present invention is to provide a frame assembly and dunnage bar locking arrangement in which the bar is secured to the frame for vertically holding the dunnage against holding rails in the bottom of the frame, and/or in which the locking bar is releasably secured to the frame both in the dunnage-engaging position of the locking bar, and in the position of the locking bar remote from the dunnage-engaging position for loading and unloading dunnage to and from the frame. A further object of the present invention is to provide a frame assembly and dunnage bar lock arrangement in which the latch bolt is contoured for improving operation thereof in the event of slight misalignment between the locking bar and strikers on the frame.